Abstract
Applications of digital signal processing technology to electric power systems have received a great deal of attention in recent years. There have been many digital algorithm applied to calculate frequency and phasor. In those, in particular, the PMU(Phasor Measurement Unit) is widely applied in order to detect both r.m.s. value and phase angle of voltage/current at multi points in pwoer systems. The calculation algorithm of the voltage/current phasor in the PMU is based on the recursive DFT(Discrete Fourier Transform). However, in the case when the frequency of power systems is fluctuating and different from the fundamental frequency of DFT algorithm, the calculated r.m.s. value and phase angle have the detection error due to the deviation of frequency.
The purpose of this paper is to propose a new detection method of the frequency and the phasor in power systems by analyzing the error contained in the volatge phasor due to the deviation of frequency. The numerical simulation results are shown to confirm the effectiveness of the proposed method compared with zero-cross detection method. In particalar, the proposed method has robustness in the case when the voltage wave contains harmonics.
